Diekman, the top left-hander in the Texas bullpen, has battled the condition throughout his career. Rangers general manager Jon Daniels said Tuesday the team was aware of the possible surgery and absence before agreeing with Diekman last week on a $2.55 million, one-year contract to avoid salary arbitration.

The surgery is planned for Jan. 25. Diekman had a flare-up with his condition, which affects the intestines and colon, during the holidays.

The 29-year-old Diekman was 4-2 with a 3.40 ERA and four saves last season for the AL West champions. He came to Texas along with ace Cole Hamels in a deal with Philadelphia at the trading deadline in 2015.